The present invention relates generally to a broadcast data access system, and more particularly to an architecture for supporting applications that receive broadcast data from a data carousel over a broadcast network.
In a broadcast network architecture, various types of data can be delivered from a server to a group of multimedia clients. Typically, multimedia clients do not have enough resources to store all of the data that is being broadcast over the network. Even if the client could store all of the data, there is no guarantee that the client will receive an error-free copy of the data in a single transmission of the data. Moreover, the client has no way of requesting that a server resend missing or defective data. Since the data is being sent to many clients, it might also be prohibitive to resend missing or defective data to each of the clients that request it.
A broadcast data carousel is commonly used for transporting data in a broadcast environment. This underlying mechanism for transporting data is defined in the MPEG-2 DSM-CC specification (i.e., ISC/IEC 13818-6). Using this mechanism, the server repeatedly sends data over a period of time so that a client who is interested in the data may receive it only when it is required. If a client misses some of the data or receives defective data, it waits for the next broadcast of the data to receive any data that it may need.
A Broadcast File System (BFS) provides a layer on top of the broadcast data carousel that hides the details of the underlying transport mechanism from the server and clients. In particular, BFS creates a mapping between the carousel/file number and a module name. As a result, the server and clients view the broadcast data as a standard hierarchical file system similar to files found on a disk operating system.
Therefore, it would be desirable to provide a broadcast data access system for receiving broadcast data from a data carousel in a simple, efficient, and flexible manner. It should support multiple data sources between the broadcast network and the multimedia client, such that each source can receive a different form of encoded broadcast data. In addition, the broadcast data access system should be able to efficiently process data packets received in a non-sequential order, as well as simultaneously fulfill multiple requests for the same data packets by different applications. To lessen processing overhead, filters are dynamically installed on the client. Lastly, the present invention should provide a method for downloading and synchronizing a directory module with the content of the data carousel being broadcast to the client.